[BIO] VITAMIN DEFICIENCY

Question 1

thiamine function

Answer 1

forms TPP by an ATP dependent enzyme in liver

Question 2

reactions requiring TPP

Answer 2

1- oxidative decarboxylation of α-ketoacids
2- transketolase reactions
3- decarboxylation of pyruvic acid in yeast
4-branched chain AA catabolism

Question 3

oxidative decarboxylation of α-ketoacids

Answer 3

pyruvate to Acetyl CoA
α-ketoglutarate to succinyl CoA
branches

Question 4

decarboxylation of pyruvic acid

Answer 4

pyruvate to Acetylaldehyde

Question 5

Thiamin enzymes (4)

Answer 5

1- PDH
2-α-ketoglutarate dehydrogenase
3- Transketolase
4- Branched-chain ketoacid dehydrogenase

Question 6

which pathways is Thiamine involved in?

Answer 6

PDH
TCA
HMP
Branched-chain AA catabolism

Question 7

Thiamin deficiency causes

Answer 7

decreases pyruvate & ketoglutarate dehydrogenase activity—>decreased ATP–> impaired cellular functions

Question 8

diseases associated w/ thiamin deficiency

Answer 8

Beriberi= polished rice diet
Wernicke-Korsakoff syndrome= seen in alcoholics

Question 9

why is Wernicke-Korsakoff syndrome commonly found in alcoholics?

Answer 9

alcohol impairs Vit B1 intestinal absorption

Question 10

biochemical tests of thiamine status (5)

Answer 10

1- Blood thiamine
2- Erythrocyte transketolase activity
3- Thiamine pyrophosphate effect
4- Urinary thiamine
5-Blood pyruvate & lactate levels

Question 11

PDC role

Answer 11

converts pyruvate to acetyl CoA
to produce citrate

Question 12

PDH deficiency

Answer 12

1- pyruvate-> acetyl CoA pathway interrupted
2- pyruvate shunted to produce lactic acid + alanine
3- citrate production= limited
4- citric acid= can’t proceed

Question 13

how is acetyl-CoA produced in case of PDH deficiency

Answer 13

alternate metabolic pathways are stimulated but energy deficit remains in CNS

Question 14

clinical picture of PDH deficiency (7)

Answer 14

lactic acidosis
hypotonia
lethargy
poor feeding
structural abnormalities in brain
seizures
neuropathological spasms

Question 15

symptoms of PDH usually progress to

Answer 15

mental retardation
microcephaly
blindness
spasticity

Question 16

TTT of Thiamine deficiency

Answer 16

dietary restriction of Carbohydrates
acidosis correction

Question 17

niacin contains

Answer 17

pyridine ring

Question 18

nicotinic acid

Answer 18

pyridine-3-carboxylic acid

Question 19

sources of vitamin B1

Answer 19

yeast
bran
green vegetables
grains
nuts
legumes
liver
kidneys
heart
eggs milk

Question 20

sources of vitamin B3

Answer 20

grains
cereal
milk
liver

Question 21

food low in niacin & tryptophan

Answer 21

corn

Question 22

niacin is derived from

Answer 22

tryptophan
60mg tryptophan produces 1mg niacin

Question 23

niacin synthesis requires?

Answer 23

Vitamin B6

Question 24

nicotinamide deamination occurs in?

Answer 24

the body

Question 25

nicotinamide is important for

Answer 25

NAD+ & NADP+ synthesis

Question 26

NAD+ & NADPH+ role?

Answer 26

1 electron 1 hydrogen atom carriers

Question 27

NAD+ & NADPH+ are coenzymes for?

Answer 27

dehydrogenases in oxidation-reduction reactions

Question 28

Nicotinic acid therapeutic role?

Answer 28

lowers plasma cholesterol & TAG
(-) lipolysis
decreased circulating FFAs

Question 29

Niacin deficiency causes

Answer 29

Pellagra

Question 30

Pellagra affects?

Answer 30

skin
GIT
CNS

Question 31

Pellagra symptoms

Answer 31

Dermatitis
Diarrhea
Dementia, demyelination
Death

Question 32

Niacin deficiency is caused by

Answer 32

tryptophan & Niacin poor diet
defective tryptophan absorption (Hartnup’s disease)
Vit B6 deficiency
Carcinoid tumor

Question 33

how does carcinoid tumor cause niacin deficiency

Answer 33

by excessive tryptophan utilization to produce serotonin

Question 34

treatment of niacin deficiency

Answer 34

ttt of cause
nicotinic acid supplements